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A model supersonic buried-nozzle jet: instability and acoustic wave scattering and the far-field sound

Samanta, Arnab and Freund, Jonathan B (2015) A model supersonic buried-nozzle jet: instability and acoustic wave scattering and the far-field sound. In: JOURNAL OF FLUID MECHANICS, 778 .

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Official URL: http://dx.doi.org/10.1017/jfm.2015.354

Abstract

We consider sound source mechanisms involving the acoustic and instability modes of dual-stream isothermal supersonic jets with the inner nozzle buried within an outer shroud-like nozzle. A particular focus is scattering into radiating sound waves at the shroud lip. For such jets, several families of acoustically coupled instability waves exist, beyond the regular vortical Kelvin-Helmholtz mode, with different shapes and propagation characteristics, which can therefore affect the character of the radiated sound. In our model, the coaxial shear layers are vortex sheets while the incident acoustic disturbances are the propagating shroud modes. The Wiener-Hopf method is used to compute their scattering at the sharp shroud edge to obtain the far-field radiation. The resulting far-field directivity quantifies the acoustic efficiency of different mechanisms, which is particularly important in the upstream direction, where the results show that the scattered sound is more intense than that radiated directly by the shear-layer modes.

Item Type: Journal Article
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Additional Information: Copy right for this article belongs to the CAMBRIDGE UNIV PRESS, 32 AVENUE OF THE AMERICAS, NEW YORK, NY 10013-2473 USA
Keywords: acoustics; aeroacoustics
Department/Centre: Division of Mechanical Sciences > Aerospace Engineering (Formerly, Aeronautical Engineering)
Date Deposited: 11 Sep 2015 04:33
Last Modified: 11 Sep 2015 04:33
URI: http://eprints.iisc.ernet.in/id/eprint/52316

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